I have just committed the last piece to get automatic updates of SIP Communicator on MacOSX. This auto-update feature is based on the Sparkle framework [1] for MacOSX.

From build 1101 [2], you'll get automatically notified when a new version of SC is available (on startup, then every day), and the auto-updater will take care of downloading the new version, installing it, and relaunching SC. It's a very convenient feature and I hope you'll give it a try and provide me some feedback here